Automotive vehicle seats typically provide for a whole range of adjustments aimed at enhancing occupant comfort and safety. These adjustments typically include forwards and backwards movement to enable the position of the seat on the longitudinal axis of a vehicle to be adjusted, upward and downward movement to enable the position of the seat on the vertical axis of a vehicle to be adjusted and pivotal movement of a seat squab part relative to the cushion part to enable rake of the squab relative to the seat to be adjusted.
The mechanisms inherent to the provision of these adjustments impart a degree of play or compliance to a seat. This presents a problem under vehicle impact conditions in that movement of a seat relative to a vehicle as a result of compliance in its adjustment mechanisms will contribute to movement of an occupant of the seat relative to the vehicle during impact conditions. This movement generally counters the intended effects of safety devices such as seat belts and airbags intended to restrain and control movement of vehicle occupant during an impact and can therefore increase the risk of an occupant incurring an injury.
As automotive vehicle seats have become more complex so their mass has increased and this exacerbates the problem since the increased mass results in increased forces being generated by the seat when a vehicle is involved in an impact. The problem is further exacerbated where a vehicle seat is provided with an integrated seat belt mounted on the seat rather than directly to the vehicle. With this arrangement force applied to the seat belt by an occupant during a vehicle impact is transmitted to the vehicle seat rather than directly to the vehicle. This further increases the load upon the seat and generates further movement of the seat relative to the vehicle.
Embodiments of the present invention have been made in consideration of these problems.